Bearing metal



Patented Jane 14, 1927.

Mrs s PAUL KEMP AND THEODOB KITTL, OF VIENNA, AUSTRIA.

BEARING METAL.

No Drawing. Application filed August 1'0, 1925, Serial No. 49,450, and in Austria August 23, 1924.

This invention relates to .alloys of theternary system lead-tin-antirnony containing a high percentage of lead and a considerably smaller amount of tin, which alloys show qualities. as suitable for use as bearing metals just as good as alloys containing a high percentage of tin.

For obtaining such result trials have already been made for preventing segregation and increasing the hardness by adding a few per cent of copper to alloys showing approximately the composition: 80% lead, 10% antimony, 5% tin. Furthermore it has been proposed to improve alloys containing a high percentage of lead, with about 15 to 25% of antimony and about .3 to 6% of tin, by adding simultaneously about 1 to 3% of nickel and 0.6 to'-1.5% of cop er Adding to such alloys, both nickel an copper, in

the ratio stated is claimed to give the sur pr1smg effect ameliorating alloys poor in tin to sue degree, as to render them equivalent to alloys with high tin contents. It has been proposed also to add insignificant quantities ofdphosphorus or'arsenic (withthe nickel 'an copper), added for augmenting to a small degree the hardness of the resulting alloy. For this purpose it has been proposed to add the 0.6 to 1.5% of copper in the form of phosphor-copper (of which 0.8 to 2.2% were added) or else, to replace the phosphorus totally or {partly by arsenic, which was regarded as an equivalent of phosphorus.

The present invention is based on the' knowledge gained in the course of exhaustive experiments, that alloys of the ternary system lead-tin-antimony with high contents of lead and a low percentage of tin can be made equivalent in respect of all the essential' properties, to bearing metals of'said ternary system with a high tin contents by adding appropriate quantities of arsenic only without addition of other metals. According to the invention, for hearing metals containing about to 77% of lead, 3 to 14% of tin and 10to 27% of antimony the quantity of arsenic to be added amounts to from 0.7 to 2.5%. p

The efiect resulting from the addition of arsenic is based on two distinguished proceedings, which both must co-act and which cannot be provoked by the addition of phosphorus. Thesaid two proceedings are the following:

1. Arsenic forms with lead and antimony a ternary eutectic, which is considerably harder than the binary eutectic lead-antimony.

2. Arsenic forms with tin a hard tinarsenic compound, the composition of which is most likely Sn,As

From these two facts a very considerable increase of hardness andcompressive strength of the alloys results. ltlorcovcr the latter also answer in respect of upsetting capability and sliding qualities all the requirements demanded from bearingmetals with high tin contents.

In the journal Metallurgie of Borchers and Wiist, 1912, page 423, table I, amongst a great number of summarily enumerated lead-antimony-tin' alloys also an alloy containing 0.5% of arsenic is indicated, but there is no indication whatever, from which the essential importance of limited arsenic contents ofthe alloys in question could be derived. In fact, the amount of 0.5%, as intin-arsenic compound, the essential agent which brings about the amelioration of the bearing metal, is not formed to a sufiicient extent. 'Moreover, arsenic containing bearing metals are also mentioned in the journal Zeitschrift fiir Metallkunde, 1923, Tome 15, pages 165 and 166, particularly in the table page 165. These alloys however, do not contain any tin, whilst according to the present invention a certain although small amount of tin is indispensable, as the essential condition for the amelioration of the main alloy consists of the formation of the above mentioned tin-arsenic compound.

As this tin-arsenic compound must be present in the alloy in not too small an amount, ifa substantial influence on the qualities of the bearing metal ought to be obtained, the contents of arsenic must not go below a certain limit. The lower limit has been stated to be at about 0.7%. I

As examples of carrying the invention into practice the following compositions may be given:

1. 5% tin, 25% antimony, 1 to 2% arsenic, the remainder lead. This alloy has a compressive strength of 1650 to 1700 kilogrammes per ting capability of 25% and a hardness of 31- to 33 degrees Brinell.

square centimetre, an upset- 2. 12% tin, 10% antimony, 2% arsenic, the remainder lead. The compressive strength of this alloy is about the same as that of the alloy according to Example 1,

' upsetting capability and hardness are a little less (hardness about 29,degrees Brinell) As an essential advantage of these alloys in'comparison with known alloys having similar percentages of tin, antimony and lead it is to be pointedout, that by the omission' of copper as a constituent of the alloy the noxious action of the copper-antimony compounds, is excluded, which particularly in lead alloys exercises anunfavourable effeet. If the hardening is efiected by the addition of nickel, the upsetting capability of the alloy is considerably diminished and its melting zone is enlarged, owing to the" high melting point of nickel. For this reason, when employing hearing metals with nickel contents certain prescriptions for casting are to be closely observed, as otherwise strong segregation would occur andthe effective constituent, the nickel, should be eliminated in the form of diflicultly fusible sweepings. e

The alloys made according to the present invention are exempt of these drawbacks, but on the other hand show all the advantages of bearing metals with high tin contents. Moreover the alloys made according to Example 2, owing to their nearly eutectic composition, have a very narrow -melting zone and in general a particularly low melting temperature, they can therefore be handled very easily and require 'no special cautions for casting.

We claim:

1, Bearing lead, 344% tin, 10-27% antimony and 0.7 to 2.5% arsenic.

metals consisting of 65-77% 2. Bearing metal consisting of 68 to 69% lead, 5% tin, 25% antimony, and 1-2% of arsenic.

In testimony whereof we have aflixedour signatures.

' PAUL KEMP.

THEODOR KITTL. 

